Io Volcano Culann Patera . ... Credit Copyright: Galileo Project , JPL , NASA Explanation: What causes the unusual colors surrounding Io's volcanoes? Io , the innermost large moon of Jupiter , is known to be the most tumultuous body in the Solar System . ... The robot spacecraft Galileo currently orbiting Jupiter has been monitoring the active volcano Culann Patera over the past few years. ... Green colors may arise when these processes affect the same terrain. ... NASA Official: Jay Norris. ...